1. Field of the Invention
This invention pertains to plastic compositions containing polyurethane (including, without limitation, rigid foams, semirigid foams, flexible foams, and rubbers). More specifically, the present invention covers plastic compositions containing polyurethanes and certain triesters of pentavalent phosphorus acid as non-scorching flame retardants for said plastic compositions.
2. Description of the Prior Art
Polyurethanes and utility thereof are known in the art as exemplified by Polyurethanes, B.A.B. (Reinhold Plastics Application Series), Reinhold Publishing Corporation, New York, 1965, and Modern Plastics Encyclopedia 1972-1973, Vol. 49; No. 10A, October, 1972, pages 110, 112, 162, 276, 278, 279, 282 and 283 and which publications are incorporated herein by reference.
The need for flame retarding polyurethanes has also been recognized in the art as exemplified by U.S. Pat. No. 3,347,822 and Modern Plastics Encyclopedia, ibid, pages 222, 456-458 and which publications are in toto incorporated herein by reference.
The use of various prior art materials as flame retardants for polyurethanes has often resulted in certain disadvantages such as thermal migration, head instability, light instability, hydrolytic instability and foam discoloration. Thus, there is always a demand for a material which will function as a flame retardant in polyurethanes and concurrently will not, by incorporation therein, adversely affect the chemical, physical, and mechanical properties and the appearance of the resultant polyuethane composition. This is particularly true with respect to materials which will function as flame retardants in polyurethanes without scorching or discoloring the resultant polyurethanes compositions. For while many of the prior art compounds may function as effective flame retartands in polyurethanes, they may nevertheless adversely affect the color properties of the polyurethanes.
In certain applications and uses of flame retardant poyurethane compositions it is imperative that there be no discoloration thereof. The prior art problem of providing a flame retarded non-scorching polyurethane composition has now been substantially solved by the present invention.
In U.S. Pat. No. 3,132,169, to Birum et al., teaches the use of certain phosphorobromidochloridates and triesters, containing both chlorine and bromine, of pentavalent phosphorus acid as flame retardant agents for polyurethane. However, not all of the compounds taught by the prior art, when incorporated into polyurethane, will result in nonscorching polyurethane compositions. Applicant has discovered a certain narrow and specific class of compounds which, when incorporated into polyurethanes, will provide flame retardancy thereto without discoloration thereof.